Walk: Pokéwalker
Its base catch rate is 45 out of 255 (higher is easier); the catch rate calculator works out your odds with each ball. For the look, the best colour match is Dive Ball or Quick Ball.
Evolution: Wingull → Pelipper (Level 25).
Pelipper in every game · Pokémon HeartGold & SoulSilver interactive map (Johto & Kanto)